Soaps, cleaning solutions, and other chemicals used in hospital, laboratory, restaurant, and other environments are shipped in and dispensed from bottles, bladders, or other vessels. To access the contents thereof, the vessels may be drained by gravity or dispensed by pumping systems either integral with or discrete from the vessel. Vessels drained by gravity are often more desirable than pumped dispensing system, due to the service and maintenance issues associated with pumps. In general, two types of vessels that drain by gravity are available: open systems and closed systems. In open systems, a volume of contents drained from the vessel is replaced by a substantially equivalent volume of air (much like water dispensing systems that utilize refillable water jugs). In closed systems, a volume of contents drained is not replaced by a substantially equivalent volume of air and the vessel collapses under the vacuum created by the draining action. Closed systems may be desirable to limit the exposure to the contents to the air outside the vessel for quality or other purposes. In a closed system, if the vessel collapses in an uncontrolled manner (otherwise known as a “free collapse”), access to an amount of the contents may be prevented, resulting in wasted product. For example, a bladder may fold over, preventing a portion of the contents from draining. Conversely, if the vessel does not collapse sufficiently, an amount of product may remain in the vessel, again leading to wasted product.
It is against this background that the present disclosure is made.